A rather topical question, on which VAZ engines the valve does not bend, will probably interest every owner of a car from a legendary domestic manufacturer - old or new - without much difference. The fear of a broken belt for some drivers even turns into a kind of paranoia: they begin to carry a spare belt with them, study the condition of the worker at every opportunity, consult with all friends and acquaintances who have at least something to do with the auto business. But can such actions always lead to the planned result?
On which VAZ engines the valve does not bend, you need to know for sure, and this data will strengthen your understanding: will it be necessary to repair, in addition to replacing the belt when it breaks, also the engine? After all, this procedure can take a lot of effort and, most importantly, money.
A bit of history
It is not difficult to remember engine modifications on models. But everything is in order! The first were 8-valve engines (1.5 and 1.6 liters). They did not bend the valve. And all - for a simple reason: the pistons in the intended design did not meet in the event of an incident with valves.
The developers got around the potential problem quite well, credit to them for this and praise (how many this feature saved from unplanned and rather expensive repairs)! A little later, at that time a new motor.With all the improvements and increase in horsepower up to 92(since 76), which was a clear plus, this motor also had some, not immediately noticeable drawbacks. The design of the mechanism has been changed thanks to a new head (16 valves). And as a bonus - the meeting of the pistons with the valves in the event of a timing break (at the most inopportune moment, as a rule)!
As a result- the valves were bent on this model unambiguously. And the car owner was expecting a fairly expensive repair, costing a pretty penny. The reason, in addition to a broken belt, is simple - the very design of a 1.5-liter engine with 16 valves: the pistons do not have special sub-valve recesses and, as a result, hit the valves hard. There is a bend in these parts, popularly called: the valve is bent.
Fixing bugs: But a few years have passed, and the designers have revised their concept. At 2112, they began to mount new engines of 1.6-liter volume, also 16-valve. In these modifications, little has changed from the previous ones, but there were recesses for valves on the pistons, which made it possible to avoid meeting these parts when the belt breaks, and hence costly repairs.
All repeats
Not so many years have passed yet, the happy owners of these VAZ models have already begun to get used to the good. Moreover, when the belts break, the valves on the engine do not bend, injuring it from the inside. But it was not there! The domestic auto industry does not allow to relax even for a minute. Priora appears on the horizon (updated ten), a seemingly modern machine, quite decent for many. Engine - 1.6 liters, 16 valves. Motorists thought that such annoying flaws would not happen to him.
However, as practice has shown, when the belt breaks on the Prior, the valves still bend (that is, they also meet the pistons, as on the very original 16-valve mechanisms). And who, one wonders, needs this: an additional repair at the present time, costing a pretty penny? After all, the repair of the Priorov engine will cost even more than the usual dozen.
One thing pleases, the probability of such a flaw is nevertheless minimized by the designers: the belt is much wider and it breaks not so often. But sometimes it breaks! Or, for example, a defective spare part may come across, and the likelihood of a rush will increase significantly. What to do then? You will have to repair the engine already, and not just put a new belt. Because it is not possible to predict when this can happen with hidden defects.
It remains only to make a wish so that this breakdown does not occur somewhere in an open field, where cars do not pass often, but in a city with the ability to tow your car.
By the way, to Kalina they also install engines similar in methods of destructive action on valves, only 1.4 liters (16-valve). So, as they say, be vigilant and know: on which VAZ engines the valve does not bend, and on which it does! There you will already have to constantly monitor and check the condition of the belt and take preventive actions to prevent timing gusts.
One of the scary topics in the conversations of motorists is why valves bend, on which cars this breakdown is possible, and how to prevent it. Today we will talk in detail about the reasons why the engine valves fail and the measures to prevent this malfunction.
What are the valves in the engine responsible for?
Let's start with a little theory. Surely every motorist knows how many cylinders are in the engine of his car, but how many valves are in it - not everyone will answer this question. In most modern engines, there are from eight to sixteen valves (two or four per cylinder), there are power plants (eight or twelve-cylinder) in which the number of valves is from 24 to 32.
The valve is an important part of the gas distribution mechanism (timing) of the engine of the machine, which is located in the cylinder head, is responsible for the timely supply of air to the cylinder and the expulsion of exhaust gas from it.
Moreover, the same valve cannot perform these functions, and therefore each cylinder is equipped with two types of valves - inlet valves, which supply air to the combustion chamber, and exhaust valves, which squeeze out the products of combustion of the air-fuel mixture from this chamber.
There are engines that have two exhaust and intake valves per cylinder, and there are those where there are more intake valves than exhaust valves (three and five-valve cylinders). In the structure of the valve, two parts are distinguished: a plate and a rod. It is the valve stem that gets hit when one of the elements of the gas distribution mechanism fails.
The valves are put into operation by a camshaft, which, rotating around its axis in the cylinder head, raises some and lowers other valves into the cylinders - these are the so-called gas distribution phases. In turn, the camshaft drives the crankshaft - both of these timing elements are interconnected by a drive, which can be gear, belt or chain. The gear drive rotates the camshaft in the cylinder block, while the belt or chain drive rotates the camshaft in the cylinder head.
Currently, the most widely used engines are used in the gas distribution mechanism. The belt drive type is simpler in design, but less reliable than the chain drive. The chain type of drive, in turn, is more complicated - its mechanism includes tension rollers and dampers. It is no coincidence that we paid so much attention to the details of the gas distribution mechanism - understanding the principle of its operation will help us further determine the reasons why the valve bends.
Why valves bend
Both the belt-driven gas distribution mechanism and the chain-driven timing may come to a point when the belt or chain drive fails. A broken timing belt or stretching of the timing chain links that are not able to catch on the teeth of the camshaft gears (slippage) causes the camshaft to stop abruptly, and the crankshaft continues its movement.
At this moment, the valves are recessed into the cylinder, and the piston rises towards them. The lifting force of the piston is much greater than that of the descending valves, so the piston hits the valve disc, and the stem, unable to withstand this impact, bends or even breaks. There is a complete stop of the engine, which is not recommended to start again, so as not to provoke a more serious breakdown - failure of the pistons, which is fraught with costly repairs of the cylinder head.
How to tell if the valves are bent
It is impossible to establish by eye that when the belt breaks or the timing chain slips, the valves are bent. To do this, you need to carry out two simple operations.
To begin with, we will install a new timing belt on the rollers according to the marks and slowly scroll the crankshaft. Two to five turns are enough to determine that the valves are bent: if the rotation is free, then the valve stems are intact, if it is difficult, the valves are bent.
It happens that the crankshaft scrolls, but the valves are still bent. How to determine the failure in this case? It is necessary to measure by first unscrewing the spark plugs. If there is no compression in the cylinder, the valves are bent.
How to prevent broken valves
Let's analyze the reasons why the belt could break in order to understand how to prevent such a breakdown.
Cause 1. The timing belt has expired. Like any other consumable, the timing belt has its own service life. The car manufacturer in the instruction manual indicates the timing for replacing the timing belt - for most engines, it occurs with a run of 100-120 thousand kilometers. Of course, it is possible to hope that until this moment the belt will serve faithfully, but for greater fidelity, we recommend that you inspect the condition of the belt at each scheduled maintenance and, if necessary, replace it. In this case, we will not allow it to break, and, as a result, we will not deal with problems with bent valves.
Reason 2. Using a counterfeit timing belt. Some motorists, wanting to save money, buy non-original, cheap timing belts that break at low runs - 5-7 thousand kilometers. Advice - be responsible when buying a timing belt, it is better to pay more for this consumable than to fork out later on an expensive repair of the cylinder head.
Reason 3. Breakage of the timing pump. In the design of the gas distribution mechanism of some engines, the pump comes into contact with the belt, and if this assembly fails, it jams, as a result of which the belt rubs against the pump and frays, which leads to its breakage. The pump wears out on the same runs as the timing belt, so when replacing the belt, we recommend installing a new pump.
Reason 4. Camshaft wear. This breakdown occurs at high engine mileages (from 150 thousand km or more), and therefore is not so common. A jammed camshaft can cause the timing belt to break. That is why when buying a used car with high mileage, we strongly advise you to take a look at the condition of the camshaft.
Cause 5. Faulty attachments of the timing drive. The timing belt moves on rollers, which can also wear out, jam, which leads to a break in the belt and bending of the valves.
Although timing chain engines are considered more reliable, it happens that they bend the valve too. This happens for two reasons: the chain links are stretched or the drive attachments (tension rollers and dampers) fail. The main reason why the timing chain links are stretched is the poor-quality material from which it is made. Such a misfortune happened to Volkswagen engines in the mid-2000s: a German automaker ordered chains from an unscrupulous contractor, and they began to fail at 20-40 thousand mileage, causing valve bending. So that such motors do not bend the valves, it is necessary to periodically diagnose the timing chain and attachments and, if necessary, change them to new ones.
In addition to these methods, it is possible to prevent valve bending by making special recesses on the piston heads, which in their dimensions will correspond to the valve stems. If a belt breaks or the chain slips, then when the camshaft stops, the valve stems will not bump into the piston heads, but will enter the recesses and stop there. True, this method also has its drawbacks: an engine with such “tuned” pistons loses up to seven percent of its power. Are you ready to deforce the engine of your "iron horse" for the sake of the safety of the valves in case of failure of the timing drive?
In the fall of 2015, the Lad family of cars was replenished with the top model - the Vesta car, produced in the sedan body. When asking the question “does the valve bend on the Lada Vesta”, you need to clearly understand what kind of engine we are talking about: about a 1.6-liter Russian or Nissan, or maybe about the latest development of the VAZ with the name “21179”.
Here are considered options related to cars produced now or those that will begin to be produced in the near future. Also, an 8-valve engine was developed for Vesta - it certainly does not bend the valves and will definitely not be installed on top-end sedans in 2016.
Read more about the engines that the Lada Vesta line is equipped with in the material: !
ICE VAZ-21129, 106 "forces" (pressure valve)
Under the hood of a 106-horsepower Lada Vesta
A bit of history. Motor 21129 is a modified version of another engine, namely 21127. The last of them, when the timing belt broke, successfully bent its valves, although grooves were made on the pistons ( fig. 1). The point is that the depth of the grooves was not sufficient: under certain conditions, the valve “met” with the piston with all the ensuing consequences.
With the transition to a new generation of internal combustion engines, that is, to 21129, the design of the pistons was finalized. But the external form has not changed much, and although the recesses remain, their depth is still insufficient.
Here the question was considered whether the Lada Vesta valves with the 21129 engine bend. And the answer was unequivocal: yes, oppression.
In theory, the problem with valve bending is typical for all VAZ engines equipped with 4 valves per cylinder. Each new 16-valve "inherits" it. An exception is one rarity - the VAZ-2112 internal combustion engine, the volume of which is 1.6 liters. There, the recesses are made to last (Fig. 2).
122-horsepower engine "21179" (valve oppression)
In terms of its design, the VAZ-21179 internal combustion engine does not differ much from its predecessors. The working volume was increased to 1774 ml, which was achieved by changing the piston stroke length: it was 75.6 mm, it became 84.0 mm.
Elements of the connecting rod and piston group
The piston itself is now better fitted to the cylinder than in the 21127 and 21129 engines. The distance from the piston pin to the bottom of the pistons has increased by 1.3 mm to 26.7 mm. But deeper grooves in the bottom did not appear. The timing mechanism still drives the belt, and when it breaks, no one canceled the possibility of bending the valves.
Now we know if the valves on the Lada Vesta with a 1.8-liter engine bend. The answer will be the same as for all 16-valve VAZ internal combustion engines (with the exception of 2112). The problem with the transition to a new generation remains the same. And they do not intend to return to the "heavy" pistons at the VAZ.
The timing drive on engines 21179 is equipped with not one, but two tension rollers. What is done then, so that the design is less susceptible to stretching of the timing belt.
It says here: the number of tension rollers is two
One of the automatic tensioners may jam, but then its function will be taken over by the second automatic roller.
Pistons that don't bend valves
Piston kits for some "old" 16-valve units are produced by third-party companies. These parts are supplied with deep grooves. The point is that the piston does not reach the plates and cannot bend the valves.
Tuning piston for ICE 21126-21127
ShPG elements of different engines (21127, 21129, 21179) are compatible. But you do not need to install pistons from "old engines" in Vesta's motor:
- In ICE 21129, after such “tuning”, friction losses will increase;
- If the pistons from the 26th or 27th engine are installed in the internal combustion engine 21179, the working volume will immediately change.
The "29th", as well as the "79th" Lada Vesta engine bends the valve only with "VAZ" pistons. But having installed a "tuning" part, do not expect an increase in power. And yet, using non-standard elements, you can greatly reduce the resource (lose the guarantee, get unforeseen consequences).
Nissan HR16DE engine (does not bend, there is a chain)
Disassembled HR16DE engine
There are no "deep grooves" here. Now let's pay attention to how the timing mechanism is arranged.
Nothing but gears and chains
There is no toothed belt here - a chain replaces it. It is difficult to imagine the following two situations:
- The chain could jump over the teeth of one or more gears;
- One of the elements was damaged so badly that the presence of damage led to a rupture.
As long as the chain remains intact, the valves and pistons cannot meet each other, no matter what happens to the engine. The only bad thing is that the chain can jam.
Does the Lada Vesta valve bend with a Nissan ICE? The answer "no" would be incorrect - a chain break is not ruled out. But in reality, it will be almost impossible to face such a situation. Let's see why.
Four well-known facts
The life indicator for the timing chain always exceeds the life of the engine. This is the first fact, but the condition must be met: the oil change must be timely. In general, the circuit fails gradually, and this is accompanied by symptoms:
- Audible overtones (chirring) at idle;
- At the moment of passing the “problem area”, a phase shift can be observed.
The last defect is detected using computer diagnostics.
From the appearance of any symptom to a complete break in the chain, a certain time passes. And in general, a “defective circuit” can work for a long time. This was another, fourth fact.
The consequences of a broken timing belt, an example in the video
Often, in the conversations of motorists, the phrases flash: “got to be repaired, the belt broke, the valves bent”. Of course, in such cases we are talking about the timing belt. In order to understand the causes of the “catastrophe”, let us consider in general terms the interaction between the connecting rod and piston group and the gas distribution mechanism.
This interaction is strictly coordinated, otherwise the normal operation of the engine cannot be ensured.
The principle of operation of the valve-piston system
Let's take the compression stroke as an example. When the piston, compressing the combustible mixture, approaches the top dead center, it almost comes close to the combustion chamber (on diesel engines, to the surface of the head). If at this moment any of the valves is not closed, then the loss of compression will be the lesser evil. Most likely, the valve, the core of which is rigidly held by the rocker (or camshaft cam) from above, will take the blow of the piston.
The valve bends in the event of a collision between the valve and the piston
In very rare cases, the manufacturer provides recesses in the piston crown to avoid collision. From the foregoing, I hope it is clear why the valve bends when the timing belt breaks: the camshaft stops rotating, some of the valves remain in the open position, being a “convenient target” for the pistons moving by inertia.
The coherence of the timing with the crank mechanism is ensured by the precise installation of gears or sprockets. To do this, alignment marks are made on them and at certain points of the engine.
According to the type of torque transmission, the gas distribution mechanism drive can be:
- Belted
- chain
- gear
Consider their common malfunctions that can lead to valve bending.
Timing drive device
The consequences of a broken timing belt
Some inquisitive motorists are interested in the question: is it possible to bend the valves with a starter? The answer is easy! Just do not install sprockets or gears “by marks” - and the key is to start! If the engine starts, you will immediately learn to recognize the symptoms of bent valves. Although, if you don’t “miss” much, then everything can be fixed by assembling the timing drive according to the rules.
If only one valve is bent, the engine will run unevenly. Even if it is a V-shaped "six" - hear.
If, after restoring the camshaft drive, the engine runs smoothly and develops the same power, then you are lucky and the manufacturer prudently installed pistons with sufficient recesses in the bottoms. But, unfortunately, this is not always possible. First of all, when designing a motor, the designer achieves a combination of many seemingly contradictory qualities of his “brainchild”. For example, such as efficiency and power. This can, to some extent, justify the fact that on 16-valve engines, the valves often bend when the timing belt breaks.
Such problems are especially acute for the creators of diesel engines, in which the compression and the necessary swirl of the fuel mixture determine the power characteristics. Therefore, the combustion chamber is located in the bottom of the piston and often has a whimsical shape.
On diesel engines, the valve bends more often than on gasoline
However, behind this is an accurate calculation and simulation of vortex flows on a computer. Such chambers are called undivided and it is not advisable to make recesses for the valves from the point of view of high-quality atomization and the most efficient combustion of the fuel mixture. The piston is almost very close to the head of the block. Therefore, it is not yet known for certain whether there are diesel engines on which “valve does not bend”. Although, perhaps, the human genius coped with this disaster.
Repair
bent engine valves
Never attempt to repair bent valves in any way!
Replacement, and only replacement!
If you straighten the valve “by eye”, then you risk getting yourself more trouble. A valve restored by handicraft is unlikely to be coaxial with the guide sleeve and tightly pressed against the seat. And if you want to "slightly" trim the rod, then it will work like a pump, pumping oil into the combustion chamber - no cap will hold it.
It would be prudent to make troubleshooting of other parts as carefully as possible. After all, a blow can damage the guide bushings, valve seats. There are cases when the connecting rods were bent. Breakage of rocker arms is also not uncommon.
Models of VAZ engines, the valves of which are not “afraid” of a broken timing belt:
VAZ 2111 1.5l; VAZ 21083 1.5l; VAZ 11183 1.6l (8 valves); VAZ 2114 1.5l and 1.6l (both 8 valves)
It is known that the old 8-valve “Opel” engines (such as those on the DAEWOO Nexia and Chevrolet Lanos) also calmly endure this trouble.
As a rule, if a person has at least one valve bent on his beloved car, even once, such a person is already beginning to understand that even “pieces of iron” do not have iron patience and will try to become a good owner of their “horse”.
In conclusion, it would be useful to add - watch your car, do not hesitate if there is a reason to “look under the hood”.
"Stick" - the meeting point of the valves and the piston cannot be changed.
There were no problems with valve bending when the piston and valve met on VAZ engines - it did its job perfectly. But the appearance of front-wheel drive models required new engines, since the Zhiguli engine had a chain in the block, its dimensions were not suitable for transverse installation. With the help of Porsche specialists, a 1.1 liter engine was developed. with a belt in the timing drive and an aluminum block mounted transversely. It all started with him.
With the use of the timing belt, there was a risk of its breakage, which means that it could happen " stick". But on the first engines corresponding to Euro 2, there was no such problem - the belt happened to break, but without consequences. The distance between the valves and the piston was sufficient, and when out of sync, the piston did not reach the valve.
With the advent of Euro 3 standards, a broken belt began to lead to a “meeting” of valves and a piston: a motor “strangled” by eco-standards needed to compensate for the loss of power. This can be achieved by increasing the compression ratio. The piston at its top dead center (TDC) has become closer to the valves. It turns out that as a result of the race for better ecology and power, almost all cases of belt breakage began to lead to valve bending.
This happens as follows: the timing belt breaks - the camshaft stops, but not immediately, but rotates in the same mode. The piston goes up and meets a stuck valve at TDC. Blow - the valve is bent in a weak place, under the "plate". The car cannot move on.
At best, 1-2 valves suffer, but at worst, everything. Repair involves and. The pleasure is not cheap, and most importantly - unpleasant, because who likes to open a generally serviceable engine?
How to avoid
Often " plug-in» is achieved by using non-standard pistons with special milled areas on the bottom of the piston to fit the valve shape. VAZ has such engine modifications. As a rule, these are eight-valve. Also, third-party milled pistons are used.
The inevitable increase in the combustion chamber, which can cause the engine to blunt due to a decrease in the compression ratio, is compensated by the stamping at the bottom of the piston. However, as practice shows, this measure does not always save from the “meeting” of the piston and valve. We list those motors that, according to the manufacturer, are free from the risk of a collision between the piston and valves:
VAZ 2111;
VAZ 21083;
3;
VAZ 21124;
VAZ 2113;
VAZ 11183;
.
But the only reliable means is timely. It’s just that in the case of a VAZ, it’s worth doing this more often than the manufacturer recommends. By the way, in foreign cars there are also “risk” internal combustion engines, but proper operation and timely service nullify the negative statistics of “plugs”.
